Added null check to CorsPolicyBuilder

[chrispickford]

It was noticed that there is no null checking in the CorsPolicyBuilder.GetNormalizedOrigin method after a NullReferenceException was picked up. In the case that a null string is passed to the method via WithOrigins (in our case it was because a configuration file read failed) this change throws an ArgumentNullException which gives a clearer indication of what has failed.

Addresses #19830

[dnfclas]

All CLA requirements met.

[analogrelay]

Seems reasonable to me. Thanks for the fix!

[ghost]

Hello @anurse!

Because this pull request has the auto-merge label, I will be glad to assist with helping to merge this pull request once all check-in policies pass.

p.s. you can customize the way I help with merging this pull request, such as holding this pull request until a specific person approves. Simply @mention me (@msftbot) and give me an instruction to get started! Learn more here.

[analogrelay]

Looks like the test you added is failing:

Assert.Throws() Failure

Expected: typeof(System.ArgumentNullException)

Actual: typeof(System.NullReferenceException): Object reference not set to an instance of an object.

---- System.NullReferenceException : Object reference not set to an instance of an object.

Looking at sharplab, what your test actually does is pass a null array rather than an array with a null item.

Working with params is a little tricky, as you can see since I approved the change without realizing this would happen! Good thing we have tests!

I'd suggest a few changes here:

1. Add a null-check directly on WithOrigins and keep the current test you've added

2. Add a second test that explicitly constructs an array with an empty element and passes it to WithOrigins (i.e. .WithOrigins(new string[] { "foo", null, "bar" })) and validate that the inner ArgumentNullException is properly thrown.

I think that will resolve the issue and add a little more coverage here.

[mkArtakMSFT]

@chrispickford you still haven't addressed @anurse 's comment regarding what you're actually testing. Your test doesn't match your change. Do you want to give this another try?

[chrispickford]

@mkArtakMSFT @anurse Apologies for the delay, I've updated the test and added extra null check.

[chrispickford]

@anurse @Tratcher I'm not sure what's going on with the CI build. Any pointers?

[mkArtakMSFT]

Closed and reopened the PR to re-trigger the build

[mkArtakMSFT]

@anurse this is blocked on you to sign-off.

[analogrelay]

I’m not able to do it from my phone but I’m happy to have my review dismissed to unblock merging if there are other approving reviews.

Addressed